Taking its inspiration from Welsh history and mythology, as well from the journals of a man who sailed with Captain James Cook, this second volume by a young Welsh poet and author of children's books conveys a reverence for the physical world. The earth is omnipresent. Landscape is often developed, almost created, by those who people it: ""Their ocean is blue, so blue, deeper than/ the gown you wore at Rookham."" Depicting rugged, lonely countryside and austere Antarctic seas with an equally profound respect, Fisher threads the changing seasons through disparate centuries, using nature's circularity as a unifying force. The volume climaxes in two powerful sequences: ""The Unexplored Ocean,"" which treats Cook's voyages, and the even more striking ""Scenes from a Book of Hours,"" five Christmas verses that pit the poet's need to express against the impossibility of full expression. (Aug.)